Multi-functional optical illuminators

ABSTRACT

A single piece light pipe is designed to provide dual-field, multi-color, multi-directional illumination. The light pipe is combined with a single PCB having a plurality of LEDs to create a compact illuminator that can selectively provide dark field and bright field with red, green, blue color, broad spectrum, or combination of any color in horizontal, vertical, diagonal, or combination of any direction. The single piece light pipe is compact in size and light in weight. The non-closed form option not only can further reduce the weight but also can allow arrange opening area clearance for: (1) visual aiming and alignment in application, especially for hand held application; (2) reducing illumination crosstalk to unwanted directions; and for (3) mechanical integration. The improvements allow the illuminator to read direct product marking (DPM) type of barcodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 16/614,182, entitled “MULTI-FUNCTIONAL OPTICALILLUMINATORS,” and filed Nov. 15, 2019, which claims the benefit of PCTApplication No. PCT/CN2017/084624, entitled “MULTI-FUNCTIONAL OPTICALILLUMINATORS,” filed May 17, 2017, the entireties of which are herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to the field of optical illuminators, andmore specifically, to improvements in optical illuminators for machinevision cameras and for reading direct product marking (DPM) barcodes.

BACKGROUND

Generally speaking, machine vision cameras and imaging barcode readersrequire certain specific illumination for difficult objects andbarcodes. One difficult application is direct product marking (DPM) typeof barcodes with metallic or laminated material that are commonlyadopted in the industry.

Specific illumination for these applications can includes dark field andbright field, color and broad spectrum, single and multi-direction.Traditionally, the requirement for specific illumination has beensatisfied by customized illumination systems. These conventionalapproaches suffer complicated structure with bulky optical light guide,diffuser and reflector combining with huge numbers of LEDs with lowlight efficiency. Diffused bright field illumination also suffers ghostimage of the camera opening of the diffuser in the application ofpolished object imaging.

There is a need to implement a general purpose multi-functionalillumination optical assembly to satisfy the requirement previouslyachieved with customized illumination systems.

SUMMARY

Accordingly, in one aspect, the present invention embraces devices for amulti-functional optical illuminator. A single piece light pipe may bedesigned to provide dual-field, multi-color, multi-directionalillumination. When combined with single PCB with a plurality LEDs, thecompact illuminator can selectively provide dark field and bright fieldwith red, green, blue color, broad spectrum, or combination of any colorin horizontal, vertical, diagonal, or combination of any direction. Themulti-functional optical illuminator may be capable of reading a directproduct marking (DPM) type of barcode.

In an exemplary embodiment, an illuminator may comprise a light pipewith an open frame structure for visual aiming of the illuminator tofacilitate an alignment of a barcode; and a circuit board, attached to aback opening of the light pipe, comprises six dark field LEDs forgenerating six dark field illuminations and two bright field LEDs forgenerating bright field illuminations. The two bright field LEDs mayproduce two alternating point sources for providing bright fieldilluminations in different directions to minimize a specular reflectionhot spot without using any diffuser during the bright fieldilluminations. Also, chamfered inner edges of the light pipe emit thedark field illuminations in different orientations from the light pipe.

The illuminator may selectively provide dark field illumination andbright field illumination with a red, green, or blue color, or acombination of any color, and in a horizontal, a vertical, a diagonal,or a combination of directions thereof. The six dark field LEDs maysupport red, green blue color options to achieve a preferred contrastfor different barcode backgrounds and foregrounds due to differentmaterials and surface features. The barcode may be a direct productmarking (DPM) type barcodes. A host computer, coupled to theilluminator, may provide programming information to control of the darkfield illumination and bright field illumination.

The chamfered inner edges may be textured and may be located on frontopening of the light pipe to allow an emission of dark fieldilluminations in various orientations. The six dark field LEDs may emitdark field illumination through input ports on the back opening of thelight pipe, wherein, the input ports may have no coating to minimize areduction of the dark field illumination. A camera may be mounted on thecircuit board, through an opening on the circuit board, with a lens ofthe camera viewing at the front opening of the light pipe. An exteriorsurface and an interior surface of the light pipe may be coatedsequentially with first a reflective coating and then a non-reflectivecoating. The light pipe comprises polycarbonate (PMMA) injectionmolding.

In another exemplary embodiment, a light pipe may comprise a singlepiece open frame structure; a multi-layer coating on an exterior and aninterior of the light pipe; and a front opening with chamfered lightoutput ports to provide illumination uniformity with an optimizedchamfer angle and chamfer surface texture to support emissions of darkfield illuminations in various orientations. The light pipe also maycomprise LED input ports located on a rear of the light pipe that haveno coating in order to minimize a reduction of illumination from theLEDs.

The multi-layer coating may comprise coating (i) coating a reflectivelayer to substantially achieve total internal reflection for highefficiency in dark field illumination, and then (ii) coating anon-reflective layer to minimize any light reflection in light fieldapplication. When integrated into an illuminator, the single piece openframe structure supports visual aiming of the illuminator to facilitatean alignment of an object.

Light pipe total internal reflection may suffer leakage from thegeometry details of the light pipe and may not completely satisfy thetotal internal reflection requirement. Light pipe surface defects mayalso break the total internal reflection condition. Adding reflectivecoating can effectively “substantially” reflect this leaking light backinto the pipe.

Light pipe without coating or with reflective coating may be highlyreflective to the outside light. This situation may create a problem forbright field application. When the bright field point source light ison, reflection of the surrounding light pipe may generate reflection andcreate ghost images. Non-reflective coating can “minimize” thereflection to outside light and can make bright field illumination wellcontrolled.

In yet another exemplary embodiment, a multi-function illuminator maycomprise a plurality of bright field LEDs for generating bright fieldillumination; a plurality of dark field LEDs for generating dark fieldillumination; a circuit board comprising the plurality of bright fieldLEDs and plurality of dark field LEDs; a light pipe attached to thecircuit board to transfer dual-field, multi-color, multi-directionalillumination; a controller for selectively controlling the plurality ofbright field LEDs and plurality of dark field LEDs; and a camera mountedon the circuit board, through an opening on the circuit board, with alens of camera viewing at the front opening of the light pipe.

The plurality of bright field LEDs and plurality of dark field LEDs maygenerate the dark field illumination and bright field illumination witha red, green, or blue color, or a combination of any color, and in ahorizontal, a vertical, a diagonal, or a combination of directionsthereof. The plurality of bright field LEDs may comprise two brightfield LEDs and plurality of dark field LEDs may comprise 6 dark fieldLEDs. The two bright field LEDs may provide two alternating pointsources for generating two consecutive images that are combined toprovide a hot spot free image with specular reflection minimized. Afront opening of the light pipe may comprise chamfered light outputports at the front opening of the light pipe to provide illuminationuniformity with optimized chamfer angle and chamfer surface texture tosupport emissions of dark field illuminations in various orientations.The dark field LEDs may emit the dark field illumination through inputports on a back opening of the light pipe, wherein, the input ports haveno coating.

The foregoing illustrative summary, as well as other exemplaryobjectives and/or advantages of the invention, and the manner in whichthe same are accomplished, are further explained within the followingdetailed description and its accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary embodiment of a single piece illuminatorlight pipe.

FIG. 2 illustrates another exemplary embodiment of a single pieceilluminator light pipe.

FIG. 3 illustrates an exemplary embodiment of a single piece illuminatorlight pipe and a printed circuit board (PCB) comprising eight LEDs.

FIG. 4 illustrates an exemplary embodiment of a multi-functionalilluminator.

FIG. 5 illustrates an exemplary embodiment of the viewing and alignmentof barcodes with a multi-functional illuminator.

FIG. 6 illustrates an exemplary embodiment of bright field illuminationhot spot images.

FIG. 7 illustrates an exemplary embodiment of the dark field and brightfield illumination in a multi-functional illuminator. FIG. 8 is thefront view of FIG. 7.

FIG. 8 illustrates another exemplary embodiment of the dark field andbright field illumination in a multi-functional illuminator. FIG. 8 isthe front view of FIG. 7.

FIG. 9 illustrates an exemplary embodiment of the RED-Green-Blue (RGB)spectrum of the LEDs of a multi-functional illuminator.

FIG. 10 illustrates an exemplary embodiment of a flowchart describingthe operation of a multi-functional illuminator.

DETAILED DESCRIPTION

Accordingly, in one aspect, the present invention embraces a new singlepiece multi-functional integrated illuminator with a compact size and aminimum amount of LEDs that may provide adequate illumination. Theilluminator may control LEDs selectively for dark and bright fieldillumination. Previously solutions required complicated multi-pieceoptical assembly. The alternative spot bright field illumination solvesthe hot spot problem of polished object imaging. The selectableillumination allows for efficient reading of complex barcodes, e.g. DPMbarcodes.

A barcode reader (or barcode scanner) can be an electronic device thatcan read and output the data of a printed barcodes to a computer. It caninclude of a light source, a lens and a light sensor translating opticalimpulses into electrical pulses. Barcode readers can contain decodercircuitry that analyzes the barcode's image data provided by the sensorand sends the barcode's content to the scanner's output port.

DPM barcode scanners and mobile computers are equipped with imagerscapable of reading barcodes that are etched or imprinted directly intothe surface of materials such as plastic and metal.

DPM tags are in essence Datamatrix (or QR) symbols directly marked ontoa substrate (metal, rubber, glass, etc.). There are many markingtechnologies to choose from (e.g. mechanical drilling/hammering/laseretching/chemical etching/sand-blasting/mold casting/stenciling etc.)depending on substrate type, cost, and the level of durability that canbe desired. Unlike paper-based barcodes (i.e. printed on plain paper andusually printed with black ink/thermal on white backgrounds) DPMbarcodes can be tricky to scan, for several reasons includingreflectance from the substrate and lack of contrast between the actualmarks and the said substrate. Often times these marks can even appearcompletely “washed-out” to the casual observer. Another peculiarity ofDPM barcodes is that the barcode can be made of an assortment of dotswhich can be clearly non-contiguous with each other, or be overlapped tosome degree; these marks are usually referred to as “dot-peen” when madeof recessed circular dots.

A single piece light pipe may be designed to provide dual-field,multi-color, multi-directional illumination. Combined with single PCBwith 8 LEDs, the compact illuminator can selectively provide dark fieldand bright field with red, green, blue narrow color, broad spectrum, orcombination of any color in horizontal, vertical, diagonal, orcombination of any direction. There may be applications with only brightfield illumination, or only dark field illumination.

The single piece light pipe may be compact in size and light in weight.The non-closed form option not only can further reduce the weight butalso can allow an opening area clearance for: (1) visual aiming andalignment in application, especially for hand held application; (2)reducing illumination crosstalk to unwanted directions; and for (3)mechanical integration.

The unique light-pipe design may comprises a multi-layer coating toachieve: (1) stopping light leaking from inside of the pipe to improvethe efficiency of the dark field illumination; and (2) preventingreflection of the bright field illumination to reduce unwantedillumination, which can cause ghost image when imaging smooth reflectiveobject. The multi-layer coating can include an initial coat ofreflective coating and a second coat of non-reflective coating.

The light-pipe clear opening with chamfered light output port canprovide illumination uniformity with optimized chamfer angle and chamfersurface texture. The optimized chamfer angle is designed to minimize theloss of dark field illumination when the light passes through thechamfered light output ports. The non-closed light pipe with anon-reflective exterior allows alternating dual point sources brightillumination. Commonly used in the industry is light field illuminationwith closed form light diffuser to provide diffused illumination toreduce possibility of specular reflection created hot spot in image.This solution can create difficulties for object imaging and barcodedecoding, especially for highly reflective polished surface, metallicsurface or laminated surface, such as DPM barcodes. The missing part ofdiffuser at the opening for camera can create dark ghost image. Thepresent invention can solve the specular reflection problem by using twoalternating point sources with minimum size hot spot. Combining twoconsecutive images can minimize specular reflection without need ofclosed form bright field illumination. Minimizing the specularreflection prevents the illumination of the hot spots from damaging theimaging.

FIG. 1 illustrates an exemplary embodiment of single piece illuminatorlight pipe 100, herein after “light pipe 100”. FIG. 1 includes two viewsof light pipe 100; view 102 shows the front of light pipe 100 and view104 shows the rear of light pipe 100. The exterior and interior surfaces106 of light pipe 100 include a dual coating. First, exterior andinterior surfaces 106 are coated with a reflective coating. Second,exterior and interior surfaces 106 are coated with a non-reflectivecoating. Hence, all surfaces are coated with a multi-layer coating onthe exterior and the interior of the light pipe 100.

FIG. 2 illustrate illustrates exemplary embodiment of single pieceilluminator light pipe 200, herein after “light pipe 200”. View 202illustrates the front of light pipe 200. View 204 illustrates a crosssection view of light pipe 200, including its edges that have an openingto allow light to exit from light pipe 200. The dark field light outputport 208 has a chamfer shape and a textured finish. The dark field lightoutput port 208 is located at the front opening of light pipe 200. View206 illustrated the rear of light pipe 200 including a LED light inputport 210. The light input port 210 has no reflective coating so as tominimize a reduction of the illumination from the LEDs as the lighttravels through the LED light input port 210. There are five other areasfor light input ports similar to light input port 210 on the rear sideof light pipe 200.

FIG. 3 illustrates an exemplary embodiment of single piece illuminatorlight pipe assembly 300, including and an illumination printed circuitboard (PCB) 304 and a single piece light pipe 302. Illumination PCB 304comprising eight LEDs. The LEDs include two bright field LEDs 306 andsix dark field LEDs 308. The six dark field LEDs 308 are positioned onthe illumination PCB 304 to align with the 6 LED light input ports, perFIG. 2. The two bright field LEDs 306 are positioned on a vertical axisin the center of illumination PCB 304, with one LED positioned in theupper part of the illumination PCB 304, and the other LED positioned inthe lower part of the illumination PCB 304. Illumination PCB 304 has arectangular shaped hole which supports the insertion of camera assembly406.

FIG. 4 illustrates an exemplary embodiment of a multi-functionalilluminator with a camera 400. View 402 presents a front view ofmulti-functional illuminator with a camera 400, and View 404 presents arear view of multi-functional illuminator with a camera 400, includingillumination assembly 408 and camera assembly 406.

FIG. 5 illustrates an exemplary embodiment of the viewing and alignmentof barcodes with a multi-functional illuminator 500. Single pieceilluminator light pipe assembly has an opening 502 in the top of itsstructure that allows a user to view a barcode and properly align thebarcode in multi-functional illuminator 500. View 504 illustrates theview of the barcode. Camera assembly 406 of FIG. 4 has been assembledinto multi-functional illuminator 500, as indicated by camera assembly506. FIG. 5 illustrates the application of DPM barcodes with dark fieldillumination.

FIG. 6 illustrates an exemplary embodiment of bright field illuminationhot spot images 600. Image 602 illustrates a barcode with the upper LEDturned on and image 604 illustrates a barcode with the lower LED turnedon. Two consecutive images with different hot spot can combine to form aspot free image.

FIG. 7 illustrates an exemplary embodiment 700 of the cross section viewof a multi-functional illuminator 710, including dark field and brightfield illumination. FIG. 7 illustrates the following: i) dark fieldlight output port 702, consistent with dark field light output port 208of FIG. 2; ii) see through opening 704, consistent with opening 502 ofFIG. 5; iii) bright field LEDs 706, consistent with two bright fieldLEDs 306 of FIG. 3; iv) camera assembly 708, consistent with cameraassembly 406 of FIG. 4 and camera assembly 506 of FIG. 5; and v) DPMobject 712. FIG. 8 is the front view of FIG. 7. FIG. 7 also illustratesdark field illumination with no or minimal specular reflections into thecamera assembly 708, and bright field with 2 alternating point sourcesfor specular reflection hot spot removal without a need for a diffuser.

FIG. 8 illustrates another exemplary embodiment of the dark field andbright field illumination in a multi-functional illuminator 800. FIG. 8is the front view of FIG. 7. FIG. 8 illustrates dark field illuminationwith horizontal, vertical (e.g., combining 2 dark field illuminations onthe same edge, and diagonal illuminations. FIG. 8 also illustratesbright field illuminations.

FIG. 9 illustrates an exemplary embodiment of the RED-Green-Blue (RGB)spectrum 900 of the LEDs of a multi-functional illuminator 710. FIG. 9illustrates the three primary colors and combination of the threeprimary color options.

FIG. 10 illustrates an exemplary embodiment of a flowchart 1000describing the operation of an illuminator, such as multi-functionalilluminator 710. The illuminator executes the following steps:

Receiving program information from a host computer. (step 1002);selecting and programming dark field LEDs including RGB colorcombinations, RGB intensities and dark field orientations. (step 1004);

Selecting and programming bright field LEDs including RGB colorcombinations, RGB intensities and bright field directions. (step 1006);

Initiating illumination. (step 1008) The illuminator may start withpreferred setting, such as one side dark field of one bright field.Based on the image captured and trial decode status, further adjustingmay occur causing a selection of a different field and/or a differentdirection;

Visually aiming the illuminator to align barcode. (step 1010);

Executing dark field illumination with a combination of horizontal,vertical and diagonal illuminations. (step 1012) There may be only darkfield applications, such as highly reflective surface with only surfaceprofile change or texture change markings. Also, there may be brightfield only applications, such as very low contrast marking and/or onhighly absorbing surface; and

Executing bright field illuminations with 2 alternating bright fieldLEDS (point sources for specular reflection hot spot removal. (step1014). It may be sufficient to achieve hot spot cancellation with 2alternating bright field LEDs.

In the specification and/or figures, typical embodiments of theinvention have been disclosed. The present invention is not limited tosuch exemplary embodiments. The use of the term “and/or” includes anyand all combinations of one or more of the associated listed items. Thefigures are schematic representations and so are not necessarily drawnto scale. Unless otherwise noted, specific terms have been used in ageneric and descriptive sense and not for purposes of limitation.

1. An illuminator, comprising: a light pipe with an open frame structurefor visual aiming of the illuminator to facilitate an alignment of abarcode, wherein chamfered inner edges of the light pipe are texturedand are located on a front opening of the light pipe to allow anemission of dark field illuminations in different orientations; acircuit board, attached to a back opening of the light pipe, comprisingat least one of one or more dark field LEDs for generating dark fieldilluminations and one or more bright field LEDs for generating brightfield illuminations, wherein a camera is mounted on the circuit board,through an opening on the circuit board, with a lens of the camera,viewing at a front opening of the light pipe; and wherein, the one ormore bright field LEDs produce one or more alternating point sources forproviding bright field illuminations in different directions to minimizea specular reflection hot spot without using any diffuser during thebright field illuminations.
 2. The illuminator as in claim 1, wherein,the illuminator provides at least one of the dark field illuminationsand the bright field illuminations with a red, green, or blue color, ora combination thereof, and in a horizontal, a vertical, a diagonal, or acombination of directions thereof.
 3. The illuminator as in claim 2,wherein, the one or more dark field LEDs support red, green, and bluecolor options to achieve a preferred contrast for different barcodebackgrounds and foregrounds due to different materials and surfacefeatures.
 4. The illuminator as in claim 2, wherein, a host computer,coupled to the illuminator, provides programming information to controlat least one of the dark field illuminations and the bright fieldilluminations.
 5. The illuminator as in claim 1, wherein, the barcode isa direct product marking (DPM) type barcode.
 6. The illuminator as inclaim 1, wherein, the one or more dark field LEDs emit the dark fieldilluminations through input ports on the back opening of the light pipe,wherein, the input ports have no coating to minimize a reduction of thedark field illuminations.
 7. The illuminator as in claim 1, wherein, thelight pipe comprises a polycarbonate (PMMA) injection molding.
 8. Alight pipe, comprising: a single piece open frame structure; and a frontopening with chamfered light output ports to provide illuminationuniformity with an optimized chamfer angle and chamfer surface textureto support emissions of dark field illuminations in variousorientations, wherein, the single piece open frame structure isintegrated into an illuminator and supports visual aiming of theilluminator to facilitate an alignment of an object.
 9. The light pipeas in claim 8, comprising: LED input ports located on a rear of thelight pipe with no coating in order to minimize a reduction ofillumination from a plurality of LEDs.
 10. A multi-function illuminator,comprising: at least one of a plurality of bright field LEDs forgenerating bright field illumination and a plurality of dark field LEDsfor generating dark field illumination; a circuit board comprising atleast one of the plurality of bright field LEDs and the plurality ofdark field LEDs; a light pipe, with an open frame structure, attached tothe circuit board to transfer dual-field, multi-color, multi-directionalillumination, wherein a front opening of the light pipe compriseschamfered light output ports at the front opening of the light pipe toprovide illumination uniformity with optimized chamfer angle and chamfersurface texture to support emission of the dark field illumination invarious orientations; a controller for controlling at least one of theplurality of bright field LEDs and the plurality of dark field LEDs; anda camera mounted on the circuit board, through an opening on the circuitboard, with a lens of the camera, viewing at a front opening of thelight pipe.
 11. The multi-function illuminator in claim 10, wherein, atleast one of the plurality of bright field LEDs and the plurality ofdark field LEDs generate at least one of the dark field illumination andthe bright field illumination with a red, green, or blue color, or acombination thereof, and in a horizontal, a vertical, a diagonal, or acombination of directions thereof.
 12. The multi-function illuminator inclaim 10, wherein, the plurality of bright field LEDs comprise one ormore bright field LEDs and the plurality of dark field LEDs comprise oneor more dark field LEDs.
 13. The multi-function illuminator in claim 12,wherein, the one or more bright field LEDs provide alternating pointsources for generating one or more consecutive images that are combinedto provide a hot spot free image with specular reflection minimized. 14.The multi-function illuminator in claim 10, wherein, the plurality ofdark field LEDs emit the dark field illumination through input ports ona back opening of the light pipe, and wherein, the input ports have nocoating.
 15. The light pipe as in claim 8, wherein, the object is abarcode, and wherein, the open frame structure supports visual aiming ofthe illuminator to facilitate an alignment of the barcode.